Assigm



(No Model.)

H. G. STRONG.

SPEAKING TUBE.

UNITED STATES PATENT @FFIQE.

HENRY C. STRONG, OF CHICAGO, ILLINOIS, ASSIGNOR OF ONE-FOURTH TO DAYID A. STRONG, OF SAME PLACE.

SPEAKlNG-TUBE.

SPECIFICATION forming part of Letters Patent No. 288,887. dated November 20, 1883, Application filed April 18, 1883. (No model.)

To aZZ whom it may concern:

Be it known that I, Hnxav C. STRONG, a citizen of the United States, residing in Chicago, county of Cook, and State ofIllinois, have invented certain new and useful Improvements in Speaking-Tubes, of which the following is a specification. 7

This invention relates to underground tubes for the purpose of transmitting and receiving 10 speech from one station to another.

The object of my invention is to render ordinary tubes of any desired dimensions and length available not only for communicating spoken words over long distances, but also to I 5 provide means whereby speech can be transmitted either from one end of the tube to the remaining end, or from any given point along the line alternately to the terminals thereof, as may be desired. Thislatter object I attain by availing myself of a principle in acoustics, that while soundwill travel uninterruptedly through a passage open only at the ends, yet it will not pass any opening or breakin the passage intermediate ot' the ends thereof, although the area of said opening may be less than the sectional area of the passage.

In the annexed drawings, in which devices for carrying out my invention are shown, Figure 1 represents a set of uinlerground tubes with connections made with one of said tubes in accordance with my invention. Fig. 2 is a sectional detailview ofaportion of the devices shown in Fig. l.

Referring to the drawings by letter, A indi- 3 5 eatesthe main or ulnlergroundline of tubes, which can be buried in the ground or laid in trenches or in any suitable troughs or conduits provided for their reception. These underground tubes can be of any size, material,

0 and length, and can be arranged to connect with stations at any desired points. It may also be observed that the material of which these tubes are composed is not essential, since there will be no variations in the clearness of spoken 4 5 words transmitted, by reason of the tubes being made of non-metallic substances.

In order that there shall be uninterrupted communication by sound through one end of a tube to the other, itis necessary that thetube be air-tight between its ends. A break in the communication will, however, take place should the tube be opened at any point or points between its ends.

In Fig. 1 it is intended to illustrate a station along the line, from which messages can be transmitted to or received from either end thereof, or from some other station along the line.

B indicates a tube, which, while forming a continuous portion ofthe main, is carried above ground, so that it shall be available at the station.

Under my invention I providethe elevated portion B of the main with means for allowing messages to be sent to or received from either end of the line with but one mouth-piece,a1nl, if preferred, one receiving or hearing piece at the station, the hearing or receiving piece beingprovided ioraconvenience. Thisis attained by forming holes C in the tube, at suitable distances apart, and fitting sleeves E upon said tube, so as to provide means for opening or closing said apertures. One of these sleeves carries amouth-piece, F, and to another sleeve is attached a flexible tube, G, carrying the hearing-piece G. It, now, it is desired to cstablish communication between both terminals of the line, the operator will slide the sleeves so as to close all of the openings in tube B, and hence sound will travel uninterruptedly from one end of the tube to the other.

To transmit a message from the station to either end of the line of tubing or from either end to the station, one of the apertures at one side of the speaking and hearing pieces must be opened, it being understood that in sending a message from the station the mouth-piece must be in communication with the tube B through one of the apertures, and that in receiving a message the same condition must exist with respect to the hearing-piece. Let it be supposed a person desires to send a message from the station to one end of the line in the direction indicated by the arrows in Fig. 2. He will then shift the sleeves, as in said figure, so that one of the apertures shall be uncovered, as indicated. The communication made will then pass through the tube to one end thereof,

but will not pass to the other end of the line, since it will be arrested at the opening that has been uncovered at one side of the sleeve earrying the hearing-pieces. To receive a message from the said end of the line, the sleeve carrying the mouth-piece can be shifted so as to close the opening under it, and the sleeve earrying the hearing-piece shifted over the aperture formerlyuncovered, whereby there will be a passage between the hearing-piece and the tube B.

The reverse of the above operations will be observed for transmitting a message from the station to the other end of the line-that is to say, the sleeves will be shifted so that all apertures between the mouthpiece and the said end of the line shall be closed and an aperture opened by shifting the sleeve that is shown unprovided with any attachment. It will be obvious that the sleeves, which are in the nature of valves, and the apertures made in the tube B could be arranged in a variety of ways, the only requirement being that such arrangement of sleeves and apertures shall be provided that when a message is to be sent from the station to one end of the line a passage without breaks can be established for the transmission of sound between the station and the opposite end of the line of tubing, so that a communicati on shall pass between the station and one end only of the line of tubing.

1 have found by actual tests applied to long lengths of tubing that there is a better and different result obtained by operating tubes with apertures in them, as shown in annexed drawings, through which the spoken words are transmitted and received, than where words are spoken, are transmitted and received through tubes not provided with myinvention.

In the drawings the tubing in the earth is shown to a limited extent. The pipe, tube, or

other hollow conductor of sounds is represent ed connected with the main tubing, although it may be integral therewith. In cases where tures, in which case springs might be used for normally holding the valves closed.

Having thus described my invention, what I claim, and desire to secure by Letters Patent, 1s

1'. The combination, with a speakingtube provided with a branch, and with an aperture located in the tube at one side of the branch, of means for closing the branch and aperture, to allow sound traversing the tube to pass said branch, and also operating to open the branch and aperture, whereby sound traversing the tube between the branch and one end of the tube shall be arrested at the uncovered aperture, and thereby be prevented from passing into the other terminal of the tube, substantially as described.

- 2. Aline of tubing for conducting spoken communications, provided at some point along the line with apertures, and with sliding sleeves for opening and closing the same, one of said sleeves carrying a mouth-piece and another a hearingpiece, substantially as described.

HENRY O. STRONG.

Vitnesses:

W. W. ELLIOTT, CHAS. G. PAGE. 

